Special coating material and composite material for polyhydroxyalkanoate

Abstract

The invention provides a special coating material for polyhydroxyalkanoate and a composite material, resin raw materials in the special coating material for polyhydroxyalkanoate comprise a rigid component and a flexible component, and the rigid component and / or the flexible component comprise a copolymer containing an HV monomer. The raw materials of the resin comprise rigid components and flexible components, and also comprise copolymers containing HV monomers, so that the rigidity, toughness and adhesion can be balanced as much as possible, and the polyhydroxyalkanoate does not stick to a roller and has good adhesion with paper.

Description

Technical Field

[0001] The present invention relates to the field of biodegradable materials, and particularly to a special laminating material and a composite material for polyhydroxyalkanoates. Background Art

[0002] Laminating is a film covering method. By a laminating machine, a hot-melt resin is laminated onto a substrate to form a coating, that is, a surface protective film, which can play roles such as waterproofing, moisture-proofing, and anti-oxidation.

[0003] The substrates for laminating include paper, aluminum foil, stretched polypropylene, polyester, nylon, high-density polyethylene, etc. Among them, paper is the most commonly used substrate, and a paper-plastic composite material can be obtained, which can be used for producing sturdy and durable milk cartons, frozen food containers, paper cups, etc.

[0004] Regarding the hot-melt resin, currently, polyethylene (PE) and polylactic acid (PLA) are used more frequently. In PE lamination, PE with long and short branched chains on the molecular chain and a lower crystallinity is adopted; many branched chains can destroy the regularity of the molecular structure and reduce the crystallinity; the long and short branched chains are entangled with each other, and the melt strength is relatively high. However, polyethylene is a petrochemical-based material, and the resin lamination layer is non-degradable, which will cause environmental pollution. In PLA lamination, PLA has three stereoconfigurations: dextrorotatory PLA, levorotatory PLA, and meso-PLA. Dextrorotatory PLA and levorotatory PLA are two optically active syndiotactic polymers with a crystallinity as high as about 60%. Meso-PLA is an amorphous non-crystalline material. Since the meso structure disrupts the regularity of the molecular chain, it cannot crystallize and will not become brittle due to post-crystallization. Although PLA is a biodegradable material, its degradation requires specific conditions: a relatively high temperature of 50 - 70 °C, a relatively high humidity, and a large number of microorganisms. The degradation conditions are harsh. In addition, the carbonyl group in the PLA molecular chain is coplanar with the adjacent oxygen atom and is very close to the adjacent carbon atom, making it not easy to rotate, with a low crystallinity. And due to the presence of side methyl groups, the molecular spacing is large. The barrier properties to oxygen and water vapor are poor. When applied to packaging, the protection for oil-containing foods is insufficient. Moreover, although the lamination effects of PLA and PE are good, their repulping properties are poor and they cannot be broken up.

[0005] As a new emerging material that is purely bio-based and 100% biodegradable, polyhydroxyalkanoates (PHA) are more green and bio-friendly in the processes of production, purification, and application compared with other biodegradable materials such as PLA, polybutylene succinate (PBS), poly(butylene adipate-co-terephthalate) (PBAT), and poly(propylene carbonate) (PPC). It does not require petrochemical industrial products as the synthesis source. In addition, the degradation environmental requirements are lower, and natural degradation can be achieved without composting. The paper-plastic composite material made of polyhydroxyalkanoates will not cause environmental pollution. However, when polyhydroxyalkanoates are used for lamination, there are defects such as easy sticking to the roller, easy breakage, and bubbles. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a special polyhydroxyalkanoate coating material and a composite material, which are both environmentally friendly and solve the problems of easy sticking to the roller and easy occurrence of defects such as breakage and bubbles in polyhydroxyalkanoates.

[0007] In a first aspect, the present invention provides a special polyhydroxyalkanoate coating material, wherein the resin raw material comprises a rigid component and a flexible component, and the rigid component and / or the flexible component comprises a copolymer containing HV monomers.

[0008] The existing polyhydroxyalkanoates used for coating have the following disadvantages: ① narrow processing window, poor heat resistance, severe pyrolysis above 170 °C, close to the melting temperature (Tm = 165 °C). ② low crystallization rate, long post-crystallization period, the product is prone to embrittlement due to post-crystallization, and the polyhydroxyalkanoate in the viscous flow state is prone to sticking to the roller. ③ low melt strength, prone to defects such as breakage and bubbles during coating, affecting the appearance and performance of the product. ④ high crystallinity of polyhydroxyalkanoates, difficult for molecular chains to diffuse and entangle with each other, small surface tension, and small adhesion to paper.

[0009] In view of the above problems, the present invention has found through research that using a resin raw material comprising a rigid component and a flexible component can balance rigidity and plasticity and improve processability. In addition, the present invention has also unexpectedly found that HV monomers (including 3HV, 5HV, etc.) are helpful for increasing adhesion. Through the proportion control of each component, it is possible to balance rigidity, toughness and adhesion as much as possible, taking into account that polyhydroxyalkanoates do not stick to the roller and have good adhesion to paper.

[0010] In the above technical solution of the present invention, there are three cases: ① only the rigid component comprises a copolymer containing HV monomers; ② only the flexible component comprises a copolymer containing HV monomers; ③ both the rigid component and the flexible component comprise a copolymer containing HV monomers.

[0011] Preferably, the mass ratio of the flexible component in the resin raw material is 30-40%.

[0012] Specifically, when the rigid component comprises a copolymer containing HV monomers, the copolymer containing HV monomers can be PHBV.

[0013] Further, the polyhydroxyalkanoate without HV monomers in the rigid component can be PHB.

[0014] When the flexible component comprises a copolymer containing HV monomers, the copolymer containing HV monomers can be one or more of P3HB4HB3HV and P3HB4HB5HV.

[0015] Furthermore, the polyhydroxyalkanoate without HV monomer in the flexible component can be one or more of P34HB and PHBHHx.

[0016] In some embodiments of the present invention, the resin raw materials in the special polyhydroxyalkanoate coating material include P34HB and PHBV.

[0017] In some embodiments of the present invention, the resin raw materials in the special polyhydroxyalkanoate coating material include PHB and P3HB4HB3HV / P3HB4HB5HV.

[0018] In some embodiments of the present invention, the resin raw materials in the special polyhydroxyalkanoate coating material include PHBV and P3HB4HB3HV / P3HB4HB5HV.

[0019] In some embodiments of the present invention, the resin raw materials in the special polyhydroxyalkanoate coating material include PHB, P34HB and P3HB4HB3HV / P3HB4HB5HV.

[0020] In the above technical solution, further preferably, the molar content of 4HB in P34HB is above 15%, and the molecular weight of P34HB is between 200,000 - 400,000 Da.

[0021] The molar content of 3HV in PHBV is 2 - 10%, which can be any specific value, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and the molecular weight of PHBV is above 500,000 Da.

[0022] The molecular weight of PHB is above 500,000 Da.

[0023] The molecular weight of P3HB4HB3HV is between 200,000 - 500,000 Da, wherein the molar content of 3HV is 2 - 10%, which can be any specific value, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and the molar content of 4HB is above 15%.

[0024] The molecular weight of P3HB4HB5HV is between 200,000 - 500,000 Da, wherein the molar content of 5HV is 2 - 10%, which can be any specific value, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and the molar content of 4HB is above 15%.

[0025] The molecular weight of PHBHHx is between 200,000 - 400,000 Da, wherein the molar content of HHx is above 15%.

[0026] To further improve the performance of the special polyhydroxyalkanoate film laminating material, its raw materials may further include one or more of a nucleating agent, a chain extender, an antioxidant, and a lubricant.

[0027] In some embodiments of the present invention, the special polyhydroxyalkanoate film laminating material further includes a nucleating agent and a chain extender.

[0028] Improving the crystallization rate also helps to solve the problem of sticking to the roller. Therefore, in order to improve the crystallization rate, a nucleating agent needs to be added. In some embodiments of the present invention, in order not to affect the transparency, the nucleating agent is selected from one or more of aromatic phosphate salts, sodium cinnamate, metal phosphate esters, basic metal phosphates, and sorbitol benzylidene derivatives.

[0029] A chain extender is a substance that can react with functional groups on the linear polymer chain to expand the molecular chain and increase the molecular weight. In some embodiments of the present invention, the chain extender is selected from one or more of BASF ADR 4400, BASF ADR 4468, chain extender DX-5, chain extender 6901, chain extender MSA7200, and chain extender HER.

[0030] In the special polyhydroxyalkanoate film laminating material of the present invention, the nucleating agent, the chain extender, and the polyhydroxyalkanoate that plays a plasticizing role have a synergistic effect. While shortening the molding processing cycle and increasing the crystallization rate, it can also improve the toughness of the film laminating layer without the need to specifically add toughening aids.

[0031] In some embodiments of the present invention, in order to improve the thermal processing stability, the special polyhydroxyalkanoate film laminating material further includes an antioxidant and a lubricant.

[0032] Adding an antioxidant can prevent the thermal decomposition of polyhydroxyalkanoate. In some embodiments of the present invention, the antioxidant includes hindered phenols and thioether antioxidants. Combining hindered phenols and thioether antioxidants can exert a synergistic effect, and antioxidants with a low melting point are preferred.

[0033] Specifically, in some embodiments of the present invention, the hindered phenol antioxidant is selected from one or more of common hindered phenol antioxidants such as pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, and antioxidant CYANOX 1790. The thioether antioxidant is selected from one or more of common thioether antioxidants such as distearyl thiodipropionate, dilauryl thiodipropionate, and pentaerythritol tetrakis(3-laurylthiopropionate).

[0034] In addition, the research of the present invention has found that the degradation of polyhydroxyalkanoates is significantly affected by the shear rate. For high-speed production, a lubricant is added to the polyhydroxyalkanoates to reduce the frictional heat generation between the screw and the molecules and improve the stability. In some embodiments of the present invention, the lubricant includes ethylene bisstearamide.

[0035] The additives of the present invention are selected as non-toxic or low-toxic types to reduce the pollution to the environment and the human body, so that the obtained products can be used for food-contact packaging.

[0036] Furthermore, in order to increase the melt strength, the present invention further controls the melt index of the polyhydroxyalkanoates between 5-9 g / 10 min.

[0037] In a second aspect, the present invention provides a composite material.

[0038] The composite material provided by the present invention is prepared by a lamination process from a substrate and the above-mentioned special polyhydroxyalkanoate lamination material.

[0039] Among them, the substrate can be paper, aluminum foil, stretched polypropylene, polyester, nylon, high-density polyethylene, etc.

[0040] In some embodiments of the present invention, the substrate is paper, that is, a paper-plastic composite material is obtained. Since the lamination is polyhydroxyalkanoate, the paper-plastic composite material provided by the present invention is a biodegradable composite material.

[0041] The polyhydroxyalkanoate lamination layer of the present invention has a relatively high crystallinity and certain brittleness, but it does not affect the use and can be broken during repulping. That is, it can be repulped and recycled, and the repulping rate is greater than 90%.

[0042] The paper of the present invention can be conventional paper in the art, such as white cardboard, grey board, coated paper, offset paper, corrugated paper, writing paper, kraft paper, newsprint, etc. In the embodiments of the present invention, the paper used is white cardboard.

[0043] In some embodiments of the present invention, in order to prevent hydrolysis during the processing, before the lamination, the special polyhydroxyalkanoate lamination material is dried to a moisture content of less than 0.02%; preferably, the drying condition is vacuum drying at 60-80 °C.

[0044] In some embodiments of the present invention, during the film laminating process, in order to prevent the processing degradation of polyhydroxyalkanoates, the melting processing temperature is set within the range of ±10 °C of the melting point of the special film laminating material for polyhydroxyalkanoates, and the screw speed is 120 - 150 rpm. Under these conditions, the reduction in the molecular weight of polyhydroxyalkanoates is relatively small (the original molecular weight is 600,000 - 800,000, and it is between 480,000 - 600,000 after processing). The temperature of the traction roller is set within the range of 60 - 80 °C. Heating the traction roller can enable the side of the special film laminating material for polyhydroxyalkanoates in contact with the traction roller to crystallize rapidly, reducing the adhesion to the traction roller.

[0045] The polyhydroxyalkanoate film laminating layer obtained by the present invention has a heat distortion temperature greater than 90 °C, is suitable for containing cold water and hot water, and has better barrier properties than the PLA film lamination.

[0046] In some embodiments of the present invention, during the heat sealing step after obtaining the film laminated paper, the heat sealing temperature is controlled between 250 - 310 °C, the heat sealing time is between 0.1 - 0.5 seconds, and the film lamination weight is between 25 - 30 gsm.

[0047] The present invention has found through research that when the temperature is too high and the time is too long, polyhydroxyalkanoates degrade, the molecular weight decreases sharply, affecting the heat sealing strength. Moreover, the heat sealing effect of a film lamination weight of 25 - 30 gsm is better than that of 15 - 24 gsm.

[0048] The present invention provides a special film laminating material and composite material for polyhydroxyalkanoates. Through the regulation of the polyhydroxyalkanoate system composition, the rigidity, toughness, and adhesiveness can be balanced, taking into account that polyhydroxyalkanoates do not stick to the roller and have good adhesiveness to paper. Moreover, the raw material of the special film laminating material for polyhydroxyalkanoates of the present invention is a bio - based biodegradable material. Compared with film laminations such as PLA, PE, and PP, its film laminating layer is more easily degraded in the natural environment without the need for composting. Its excellent biodegradable performance has no negative impact on the environment and helps to solve the plastic crisis. Detailed Embodiments

[0049] The term "comprising" or "including" in the present invention is an open - ended description, including the specified components or steps described, as well as other specified components or steps that do not substantially affect.

[0050] In the ranges disclosed herein, the endpoints and any values are not limited to the exact range or value. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0051] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "specific implementation manners", or "some specific implementation manners" etc. mean that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0052] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be described clearly and completely below. Apparently, the described embodiments are some embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0053] For those not specifying specific techniques or conditions in the embodiments, they shall be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. For those reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through regular channels.

[0054] The corresponding Chinese full names of the English abbreviations appearing in this article are as follows:

[0055] PHA: Polyhydroxyalkanoates

[0056] PLA: Polylactic acid

[0057] PBS: Polybutylene succinate

[0058] PBAT: Poly(butylene adipate-co-terephthalate)

[0059] PPC: Poly(propylene carbonate)

[0060] PHB: Poly-3-hydroxybutyrate

[0061] P4HB: Poly-4-hydroxybutyrate

[0062] P3HP: Poly-3-hydroxypropionate

[0063] PHBV: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

[0064] P34HB: Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)

[0065] PHBHHx: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)

[0066] P3HB4HB3HV: Poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-3-hydroxypentanoate)

[0067] P3HB4HB5HV: Poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-5-hydroxypentanoate)

[0068] TEPA: Triethyl phosphate

[0069] EBS: Ethylene bisstearamide

[0070] Antioxidant CA: 1,1,3-Tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane

[0071] Antioxidant 1010: Pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]

[0072] Antioxidant BHT: 2,6-Di-tert-butyl-4-methylphenol

[0073] Antioxidant 1098: N,N'-Hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide)

[0074] Antioxidant 245: Tris(ethylene glycol) bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate]

[0075] Antioxidant PEPQ: Tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphite

[0076] Antioxidant 168: Tris(2,4-di-tert-butylphenyl) phosphite

[0077] Antioxidant DSTP: Dilauryl thiodipropionate (sulfide type), melting point 63 - 68 °C; Antioxidant DLTP: Dodecyl thiodipropionate (sulfide type), melting point 39 - 42 °C; Radical inhibitor: 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical (melting point 69 - 72 °C)

[0078] Antioxidant 412s: Pentaerythritol tetrakis(3-laurylthiopropionate), melting point 48 - 54 °C

[0079] Example 1

[0080] This example provides a special polyhydroxyalkanoate film coating material, in which the resin raw material consists of P34HB (amorphous with a 4HB molar content of more than 15% and a molecular weight of 200,000 - 400,000 Da) and PHBV (3HV molar content of 3% and a molecular weight of more than 500,000 Da). The specific preparation method is as follows:

[0081] Step 1: Vacuum dry the P34HB and PHBV raw materials at 60 - 80°C for 4 hours to control the moisture content below 500 ppm.

[0082] Step 2: Weigh 30 parts of P34HB, 70 parts of PHBV, 0.3 part of calcium laurate, 0.5 part of nano calcium carbonate, 0.4 part of Joncryl ADR - 4400, 0.2 part of antioxidant 245, 0.2 part of antioxidant 412s, 0.4 part of carbodiimide, 0.5 part of lignoceric acid diol ester, 0.5 part of EBS, and 2 parts of epoxidized soybean oil by mass. Mix them in a high - speed mixer for 5 minutes, then pelletize them through a twin - screw extruder. Set the temperatures of each section as follows: feeding section 150°C, compression section 160°C, homogenization section 170°C, die head 175°C. The main machine speed is 200 rpm, the feeding speed is 10 Hz, and then pelletize them after water cooling and air drying to obtain a special lamination material for polyhydroxyalkanoates.

[0083] This example also uses the above - obtained special lamination material for polyhydroxyalkanoates to prepare a paper - plastic composite material. The specific method is as follows:

[0084] Put the special lamination material for polyhydroxyalkanoates into a lamination machine. Set the melting processing temperature to 160 - 200°C, the screw speed to 120 rmp, and the temperatures of traction roller 1 and traction roller 2 to be between 60 - 80°C. The extrusion die head is between traction roller 1 and traction roller 2. The material flows out through the die head and is compounded with the paper to prepare a paper - plastic composite material.

[0085] Based on Example 1, adjust the molar content of 3HV in PHBV to 2%, 4%, 5%, 7%, 8%, and 10% respectively, and keep the other conditions unchanged for parallel experiments. The results show that when the molar content of 3HV in PHBV is in the range of 2 - 10%, the same effects as in Example 1 can be achieved, and special lamination materials for polyhydroxyalkanoates and paper - plastic composite materials with good performance can be obtained.

[0086] Example 2

[0087] This example provides a special lamination material for polyhydroxyalkanoates, in which the resin raw materials are composed of P3HB4HB3HV (the molar content of 3HB is 80%, the molar content of 3HV is 3%, and the molecular weight is 20 - 500,000 Da) and PHB (the molecular weight is above 500,000 Da). The specific preparation method is as follows:

[0088] Step 1: Vacuum dry the P3HB4HB3HV and PHB raw materials at 60 - 80°C for 4 hours to control the moisture content below 500 ppm.

[0089] Step 2: Weigh 30 parts of P3HB4HB3HV, 70 parts of PHB, 0.3 part of calcium laurate, 0.5 part of nano calcium carbonate, 0.4 part of BASF ADR-4400, 0.2 part of antioxidant 245, 0.2 part of antioxidant 412s, 0.4 part of carbodiimide, 0.5 part of glycol lignocerate, 0.5 part of EBS, and 2 parts of epoxidized soybean oil. Mix them in a high-speed mixer for 5 minutes, then pelletize them through a twin-screw extruder. The temperature settings for each section are as follows: feeding section at 150 °C, compression section at 160 °C, homogenization section at 170 °C, die head at 175 °C. The main machine speed is 200 rpm, and the feeding speed is 10 Hz. Then, after water cooling and air drying, cut the pellets to obtain the special polyhydroxyalkanoate coating material.

[0090] In this example, the special polyhydroxyalkanoate coating material obtained above is also used to prepare the paper-plastic composite material, and the specific method is the same as that in Example 1.

[0091] Based on Example 2, the 3HV molar content in P3HB4HB3HV was adjusted to 2%, 4%, 5%, 7%, 9%, and 10% respectively, and the other conditions remained unchanged. Parallel experiments were carried out. The results showed that when the 3HV molar content in P3HB4HB3HV was in the range of 2 - 10%, the same effects as those in Example 2 could be achieved, and special polyhydroxyalkanoate coating materials and paper-plastic composite materials with good performance were obtained.

[0092] Example 3

[0093] This example provides a special polyhydroxyalkanoate coating material, the resin raw materials of which are composed of P3HB4HB3HV (the same as in Example 2) and PHBV (the same as in Example 1). The specific preparation method is as follows:

[0094] Step 1: Vacuum dry the P3HB4HB3HV and PHBV raw materials at 60 - 80 °C for 4 hours to control the moisture content below 500 ppm.

[0095] Step 2: Weigh 30 parts of P3HB4HB3HV, 70 parts of PHBV, 0.3 part of calcium laurate, 0.5 part of nano calcium carbonate, 0.4 part of BASF ADR-4400, 0.2 part of antioxidant 245, 0.2 part of antioxidant 412s, 0.4 part of carbodiimide, 0.5 part of glycol lignocerate, 0.5 part of EBS, and 2 parts of epoxidized soybean oil. Mix them in a high-speed mixer for 5 minutes, then pelletize them through a twin-screw extruder. The temperature settings for each section are as follows: feeding section at 150 °C, compression section at 160 °C, homogenization section at 170 °C, die head at 175 °C. The main machine speed is 200 rpm, and the feeding speed is 10 Hz. Then, after water cooling and air drying, cut the pellets to obtain the special polyhydroxyalkanoate coating material.

[0096] This example also uses the above-mentioned obtained special polyhydroxyalkanoate coating material to prepare a paper-plastic composite material, and the specific method is the same as that in Example 1.

[0097] Example 4

[0098] This example provides a special polyhydroxyalkanoate coating material, in which the resin raw materials are composed of PHB (the same as in Example 2), P34HB (the same as in Example 1), and P3HB4HB5HV (the molar content of 3HB is 75%, the molar content of 5HV is 5%, and the molecular weight is 200,000 - 500,000 Da). The specific preparation method is as follows:

[0099] Step 1: Vacuum dry the PHB, P34HB, and P3HB4HB3HV raw materials at 60 - 80 °C for 4 h respectively to control the moisture content below 500 ppm.

[0100] Step 2: Weigh 70 parts of PHB, 15 parts of P34HB, 15 parts of P3HB4HB5HV, 0.3 part of zinc stearate, 0.5 part of cyclodextrin, 0.4 part of BASF ADR-4468, 0.1 part of antioxidant 1010, 0.2 part of antioxidant DLTP, 0.5 part of polymeric carbodiimide, 0.5 part of EBS, and 2 parts of tributyl acetylcitrate by mass. Conduct physical mixing for 15 min through a high-speed mixer, and then melt-extrude and pelletize through a twin-screw extruder. The temperature settings for each section are: feeding section 120 °C, compression section 160 °C, homogenization section 170 °C, die head 175 °C. The main machine speed is 200 rpm, the feeding speed is 10 Hz, and then pelletize after water cooling and air drying to obtain the special polyhydroxyalkanoate coating material.

[0101] This example also uses the above-mentioned obtained special polyhydroxyalkanoate coating material to prepare a paper-plastic composite material, and the specific method is the same as that in Example 1.

[0102] Based on Example 4, the molar content of 5HV in P3HB4HB5HV is adjusted to 2%, 4%, 6%, 7%, 9%, and 10% respectively, and the other conditions remain unchanged for parallel experiments. The results show that when the molar content of 5HV in P3HB4HB5HV is in the range of 2 - 10%, the effects equivalent to those in Example 4 can be achieved, and special polyhydroxyalkanoate coating materials and paper-plastic composite materials with good performance can be obtained.

[0103] Performance Test

[0104] Perform performance tests on the special polyhydroxyalkanoate coating materials obtained in each example. The test methods for each index are as follows:

[0105] 1. Determination of Melt Index

[0106] The melt mass-flow rate is determined in accordance with GB / T 3682.1, with a test temperature of 190 °C and a nominal load of 2.16 kg.

[0107] 2. Determination of Tensile Strength

[0108] It is carried out in accordance with GB / T 1040.2-2006, using Type A1 specimens and a test speed of 50 mm / min.

[0109] 3. Determination of Elongation at Break

[0110] It is carried out in accordance with GB / T 1040.2-2006, using Type A1 specimens and a test speed of 50 mm / min.

[0111] 4. Determination of Izod Notched Impact Strength

[0112] It is carried out in accordance with GB / T 1843-2008, using Type B1 specimens, single-notch, and notch type C.

[0113] 5. Determination of Heat Deflection Temperature

[0114] The heat deflection temperature (HDT) is determined in accordance with GB / T 1634-2004, with a test pressure of 0.455 MPa.

[0115] The test results are shown in Table 1.

[0116] Table 1

[0117]

[0118] In addition, the paper-plastic composite materials obtained in each example are subjected to a hot coffee test, that is, the paper-plastic composite materials are made into containers and filled with hot coffee liquid (≥95 °C) for 30 minutes. As a result, there is no cracking or warping at the heat seal at the upper edge, and no leakage occurs at the bottom and the heat seal. After pouring out the coffee, there is no penetration inside.

[0119] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention, and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A special polyhydroxyalkanoate coating material, characterized in that, The resin raw material includes a rigid component and a flexible component, and the rigid component and / or the flexible component includes a copolymer containing HV monomers.

2. The polyhydroxyalkanoate special coating material according to claim 1, characterized in that, The mass ratio of the flexible component in the resin raw material is 30-40%.

3. The polyhydroxyalkanoate special lamination material according to claim 1 or 2, characterized in that, In the rigid component, the copolymer containing HV monomers is selected from PHBV, with a molecular weight greater than 500,000 Da and a molar content of 3HV of 2-10%.

4. The polyhydroxyalkanoate special coating material according to claim 3, wherein, In the rigid component, the polyhydroxyalkanoate without HV monomers is selected from PHB, with a molecular weight greater than 500,000 Da.

5. The polyhydroxyalkanoate special lamination material according to claim 1 or 2, characterized in that, In the flexible component, the copolymer containing HV monomers is selected from P3HB4HB3HV, P3HB4HB5HV, with a molecular weight between 200,000-500,000 Da, where the molar content of 3HV or 5HV is 2-10% and the molar content of 4HB is more than 15%.

6. The polyhydroxyalkanoate special coating material according to claim 5, characterized in that, In the flexible component, the polyhydroxyalkanoate without HV monomers is selected from P34HB, PHBHHx, with a molecular weight between 200,000-400,000 Da, where the molar content of 4HB or HHx is more than 15%.

7. The polyhydroxyalkanoate special coating material according to any one of claims 1-6, characterized in that, The special polyhydroxyalkanoate coating material further includes one or more of a nucleating agent, a chain extender, an antioxidant, and a lubricant; Preferably, the nucleating agent is selected from one or more of aromatic phosphate salts, sodium cinnamate, metal phosphate salts, basic metal phosphate compounds, and sorbitol benzylidene derivatives; The chain extender is selected from one or more of BASF ADR 4400, BASF ADR 4468, chain extender DX-5, chain extender 6901, chain extender MSA7200, and chain extender HER; The antioxidant includes hindered phenols and thioether antioxidants; The lubricant includes ethylene bisstearamide.

8. A composite material, characterized in that, It is prepared by a coating process from a substrate and the special polyhydroxyalkanoate coating material according to any one of claims 1-7; Preferably, the substrate is paper.

9. The composite material according to claim 8, characterized in that Before the coating, the special polyhydroxyalkanoate coating material is dried to a moisture content of less than 0.02%; Preferably, the drying conditions are vacuum drying at 60-80°C.

10. The composite material according to claim 8 or 9, characterized in that, During the coating process, the melting processing temperature is set within the range of the melting point of the special polyhydroxyalkanoate coating material ±10°C, the screw speed is 120-150 rpm, and the temperature of the traction roller is within the range of 60-80°C.

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